He hated my class, I was pretty sure. I was teaching an introductory course with enough humor and anecdotes to appeal to new majors and engage the nonmajors. But the course was more reading-intensive and academically rigorous than this particular student had bargained for, and he finished the semester with an eye on the clock and a foot out the door.

So when another student asked him, within my earshot, “Should I take that intro class with Dr. Lemuel?,” I expected him to offer a grim warning. Instead he surprised me by nodding thoughtfully and summing up a semester’s experience with me in an encouraging tone: “You’ll enjoy it. He’ll make you laugh.” A tepid endorsement, perhaps, yet far more upbeat than I had expected.

When he saw that I had overheard, he reminded me about a lecture in which I had compared the aggressive nationalism in Europe before both world wars to kids taunting each other to fight. I had playacted briefly: chin out, chest puffed, beckoning hand gestures, repeating the word “boy” in that two-syllable way that constituted fighting words back in grade school. It had gotten the laughter of recognition, especially from the males in the class, tapping a collective memory of the rituals and protocols of playground masculinity. More important (I realized, months later) my analogy had driven the point home and made a lasting impression.

A key insight from hedonic psychology and happiness metrics is that the experience of pleasure or pain (how it is sensed in the moment) is largely erased by the memory of that pleasure or pain (how it is viewed in retrospect). The duration of pleasure or pain would seem be key to the experience but actually has little impact on the memory. (For an introduction to hedonic psychology and happiness metrics, see the Nobel Prize-winner Daniel Kahneman’s 2011 book Thinking, Fast and Slow, which offers a retrospective on his career, including some of his pioneering work in this area.)

In other words, we don’t remember pleasure or pain by how long it lasts. What we remember, research shows, is a combination of the feeling of great intensity (the moment of “peak” pleasure or pain) and the impression left by the final moments of the experience (the “end,” and particularly, whether it is better or worse than preceding moments). Hence, the “peak-end” rule.

Although it was originally observed in connection with unpleasant medical procedures, the rule has been applied to other contexts by academics and popularizers. What colonoscopies and vacations have in common is that we remember not how long they last, but how they felt at the most intense moment and at the end. Surprisingly, colonoscopy patients endured longer procedures better if the extra time at the end was less painful than the earlier part of the procedure. Similarly, research participants were subjected to two tests: 60 seconds with their hand in painfully cold water for the first test, and 90 seconds in the same water for the second, but with a stream of barely warmer water providing some relief for the last half minute. Asked which of the two they would rather repeat, most participants actually chose the second. The feeling that it got better at the end overrode the fact that it was quantitatively worse.

For vacations, the peak-end rule suggests your vacation dollar is better spent on a shorter trip with some guaranteed peak experiences than a longer but uneventful stay at a resort. Vacations pass quickly, and the memories get edited down to a highlight reel. The downtime and petty hassles of travel are mostly forgotten or edited out. That is, unless the entire trip was a complete disaster, in which case the “highlights” become a blooper reel, experienced as a nightmare but retold for tragicomic entertainment.

Which brings me to college courses. Most classes are more like travel than like painful medical procedures (although I’ve taken a course or two that for sheer pleasure rivaled a colonoscopy; I just might have taught one like that, too). An academic course is like a tour with an itinerary of various destinations, the instructor pointing out the highlights along the way and coaxing student-travelers to explore the sights at each stop. But on some journeys, it’s a long ride to the intended destination, and sometimes we get delayed, detoured, or derailed by unforeseen obstacles. Those obstacles test the mettle of the guide, who has to improvise to keep the travelers engaged.

One approach is to treat students daily to in-class diversions, like a slide show, a music clip, or a YouTube video. Doing so creates a baseline experience of entertainment—constant from day to day. But taking a “peak-end” approach would aim for fewer and more carefully chosen diversions.

Over the years in different courses I’ve had occasion to show the first 20 minutes or so of the 1984 movie Red Dawn, on the topic of cold-war fear and propaganda. This Reagan-era piece of right-wing agitprop opens with a series of headlines revealing how the United States, isolated and encircled by Communist or leftist states, became ripe for a joint Russian-Cuban-Nicaraguan invasion. Parachuting into a Colorado schoolyard, the enemy invaders shoot up the school, killing the history teacher in midlecture (on the topic of Genghis Khan’s ruthless combat tactics, coincidentally).

The football team escapes into the mountains to form a guerilla resistance group, borrowing its name, the Wolverines, from the school’s mascot—taking itself completely seriously all the while, I might add. My students find that both endearing and hilarious.

Usually I’ve offered to show the film clip as an incentive for good participation in classes with a predominantly lecture and reading-discussion format. But apparently this diversion has made a more enduring impression than nearly anything else I’ve done.

That became clear to me over the past year or so, as one former student after another contacted me out of the blue to ask if I’d heard about the remake of Red Dawn, released in November (I haven’t seen the remake). Some still remember the first movie from taking my class nearly 20 years ago. As an action movie, the original film is not especially memorable. But treated academically, as an artifact, it presents a gold mine for social-science analysis. Historically it presents a snapshot of a specific mind-set in a certain era; politically it showcases the form of patriotism defined by fear, vigilance, and a siege mentality. It touches on numerous aspects of personal and social psychology, while in gender terms, there is the equivalence of sports and militancy within masculine identity.

In more recent years, students have drawn the obvious parallels between the film and the post-9/11 political-social milieu (which apparently provided the rationale for the remake, although the moment for a timely release passed about five years ago). Different students latch on to different aspects, but the subsequent discussion is consistently one of the more fruitful half-sessions of the whole course.

I usually show the film clip late in the semester, which probably extends the impression it makes. If it is the peak of students’ engagement, it is also firmly associated with how the course ended. Watching it, they felt both engaged and knowledgeable, not merely receiving instruction, but being invited to reflect on what they’ve learned, debate each other, and take ownership of the material. That made a parting impression that has apparently had a longer-than-normal duration in their minds.

I wish I could say I had all of that in mind when I first showed this particular clip, but I cannot. It was one of those serendipitous decisions made midsemester. It was like wandering into a nondescript dive restaurant and discovering the best—pick a specialty cuisine—you’ve ever had.

For me, the biggest reassurance of this experience is that it’s OK to have off days and low points in every course. You can’t possibly be always at the top of your game, week after week, and still meet all the other demands placed on college faculty members outside of the classroom. And from the standpoint of having a lasting impact on students, maybe there’s no reason to try to be.

Consistency is important, but it doesn’t have to be the unobtainable goal of consistency at one’s peak. Being reasonably good, or merely adequate throughout a course, while offering students some peak moments and a decent semester wrap-up, might actually make more of a lasting impression upon the students in the class.

In other words, what peaks well and ends well, endures well. And even this late in the semester, there’s still time left to make that lasting impression.

Author Bio: John Lemuel is the pseudonym of an associate professor in the social sciences at a small liberal-arts college in the Midwest.